Conventional water dispensers were used mainly in offices and hospitals. However, with the growing interest in safety of water and in health, the number of water dispensers used in private homes is increasing these days.
A typical known home-use water dispenser includes a cold water tank in which drinking water is stored and cooled, and a replaceable raw water container disposed at a level lower than the cold water tank. The raw water container is in communication with the cold water tank through a raw water supply line in which a pump is mounted (see e.g. JP Patent Publication 2001-153523A).
Drinking water cooled in the cold water tank of this water dispenser can be discharged e.g. into a cup. When the water level in the cold water tank falls to a predetermined value, the pump is activated to feed drinking water in the raw water container into the cold water tank through the raw water supply line.
If the raw water container is rigid enough that the raw water container is not collapsible when water remaining in the raw water container decreases, when drinking water remaining in the raw water container becomes scarce, and a negative pressure tends to be created in the raw water container, which interferes with the supply of drinking water from the raw water container to the cold water tank. This may make it impossible to use up the drinking water in the raw water container.